DEUTERATED IMPURITIES MONITORED BY MICROWAVE SPECTROSCOPY DURING GLOW-DISCHARGE CLEANING

Microwave spectroscopy was applied to monitoring of deuterated impurities produced by glow discharge cleaning (GDC). This method estimated the change in the quantity of the isotopic impurities by observing a rotational spectrum of water, HDO. For verifying the validity of the method, mass spectral behaviors of several light impurities (HDO, D2O, H2O, HD, D2 and H-2) were studied simultaneously. The deuterated species decreased with time at their own diminishing rates, while normal water, H2O, showed no decrease during GDC. The rotational spectrum of HDO stood at the frequency of 22.3077 GHz. It was distant enough from the nearest neighbor (about 70 MHz) so that the observed line was identified definitely. The lowest partial pressure detected with a microwave spectrometer was 7 x 10(-5) Pa.